1. Field of the Invention
The present invention relates to an image forming apparatus for forming an auxiliary image such as dates and marks on a recording sheet on which a main image such as a duplicate image of an original and an image based on an image information signal has been formed.
2. Description of the Prior Art
In recent years, an image forming apparatus for forming an auxiliary image such as dates and marks on a recording sheet on which a main image such as a duplicate image of an original and an image based on an image information is previously formed has been developed. In this kind of image forming apparatus, generally, a main image is formed on a recording sheet by a main image forming mechanism which uses an electrophotographic process, and then an auxiliary image such as dates and marks is formed on the recording sheet by an auxiliary image forming mechanism of a thermal transfer recording. The auxiliary image forming mechanism is disposed on the downstream side in the direction of the recording sheet transported by a fixing roller for fixing the main image formed by the main image forming mechanism on the recording sheet and generally includes a printer head of a thermal transfer recording and an ink ribbon. After the main image is fixed on the recording sheet, the auxiliary image is formed on the recording sheet by the auxiliary image forming mechanism of a thermal transfer recording.
Since the above-mentioned image forming apparatus includes the auxiliary image forming mechanism of a thermal transfer recording, an ink ribbon is required. Moreover, the printing speed is low, so that the transportation speed of the recording sheet which has passed the fixing roller should be lowered. Furthermore, the fixing roller is disposed on the downstream side of the direction of the recording sheet transported by the fixing roller, so that a distance between the fixing roller and an exit for the recording sheet should be made long, resulting in a large size of the apparatus.